Linear and cyclic guanidine derivatives, method of preparation and uses thereof

ABSTRACT

The present invention relates to linear and cyclic guanidine derivatives, method of preparation and uses thereof, pharmaceutical compositions to be used as antifungal agents, in particular against  Candida  species.

TECHNICAL FIELD

The present invention relates to linear and cyclic guanidine derivatives, method of preparation and uses thereof, pharmaceutical compositions to be used as antifungal agents, in particular against Candida species.

BACKGROUND OF THE INVENTION

The opportunistic human pathogen Candida albicans and other non-albicans species have acquired considerable clinical significance as infectious agents in immunocompromised patients, being important causes of morbidity and mortality. The recommended therapy relies on fluconazole, voriconazole and caspofungin. In fact, also many of the new possible antifungal agents that can be found in the literature possess an azole core.

The pathogenic species of Candida derive their relevance not only from the severity of the infections but also from their ability to develop resistance against a variety of antifungal agents. In fact, widespread and prolonged use of azoles has led to the rapid development of multidrug resistance, which poses a major hurdle in antifungal therapy. Many of the currently available drugs have become ineffective against new or re-emerging fungi because of the rapid development of resistance. These problems have give rise to the need to develop new effective antifungal agents. Accordingly, in the last years, new structural classes of antifungal agents were reported, among which guanidine derivatives proved to have very interesting inhibitory activity. As an example, guazatine (a mixture of guanidines and polyamines used in agriculture as fungicide) was classified as a moderately hazardous antifungal agent, while results from in vivo animal studies demonstrated a high potential for guazatine and related compounds as antifungal agents. Authors have recently reported that components of guazatine are able to act toward albicans and non-albicans Candida species.

SUMMARY OF THE INVENTION

The present invention concerns novel cyclic guanilated derivatives of different polyamines. On the basis of the results obtained with components of guazatine, new cyclic guanidine derivatives of different polyamines have been synthesized, and their biological evaluation against 8 clinical isolates and 3 reference species of Candida (C. albicans ATCC 60193, C. krusei ATCC 14243, C. parapsilosis ATCC 34136) has been carried out. The new compounds object of the invention possess an excellent antifungal activity, and they

-   -   1. are very active against different species of Candida;     -   2. have a low toxicity     -   3. are active also against drug resistant strains of Candida.

The compounds of the invention are disclosed in the enclosed claims 1-18. Such disclosure is intended to be part of the description.

It is further object of the invention any of the compounds as disclosed in claims 1-18 for use as a medicament.

It is further object of the invention any of the compounds as disclosed in claims 1-18 for use as an anti-infectious agent, preferably as antifungal agent, more preferably as antifungal agent against Candida species, even more preferably wherein the Candida species belong to the group of C. albicans, C. krusei, C. parapsilosis.

It is further object of the invention a pharmaceutical composition comprising any of compounds according to any of claims 1-18 or a mixture of any of them, and appropriate excipients and diluents. The expert in the field shall select appropriate excipients and diluents according to the way of administration (topic, oral, parenteral, etc.). In a preferred embodiment the composition further comprises at least one other compound with antifungal activity.

It is further object of the invention a process for the preparation of a compound as disclosed in any of claims 1 to 18 comprising the following steps:

a) reaction of a suitable amine R₁—NH₂ with a suitable S-methylisothiourea in a suitable solvent for obtaining compound 2

wherein n₁ and n₂ are 4 or 6, n₂ can be n₁ or n₂ can be different from n₁; R₁═H, propargyl, cyclopropylmethyl, γ-methylallyl, β-methylallyl, γ,γ-dimethylallyl, methyl or ethyl; R₂═H, propargyl, cyclopropylmethyl, γ-methylallyl, β-methylallyl, γ,γ-dimethylallyl, methyl or ethyl; b) extract and/or purify compound 2 as obtained under a); c) allow compound 2 to react with an appropriate N,N′-bis(tert-butoxycarbonyl)-N-(alkyl)-S-methylisothiourea under conditions suitable for obtaining the compound 3, or 5-10 shown below:

wherein R₂═H, propargyl, cyclopropylmethyl, γ-methylallyl, β-methylallyl, γ,γ-dimethylallyl, methyl or ethyl; R₃═H, methyl, ethyl or benzyl; R₄-R₂₃═H, methyl or ethyl; R₄-R₂₃ can be same or different; d) purify compounds 3, 5-10 as under c); e) allow compounds 3, 5-10 to react under suitable conditions for obtaining the compound according to claims 1 to 18; f) extract and/or purify the compounds as obtained under e).

It is further object of the invention an intermediate of any of formula 3, 5-10:

DETAILED DESCRIPTION OF THE INVENTION Chemistry

The compounds described in this invention can be synthesised as described below:

Examples of the synthetic procedures:

Example 1 Preparation of 1-amino-17-[N²,N³-bis(tert-butoxycarbonyl)guanidino]-9-azaheptadecane (12)

To a stirred solution of 1,17-diamino-9-azaheptadecane 3 (4.9 g, 15.06 mmol) in THF/CH₃OH 5/3 (80 mL) at 50° C., a solution of N,N′-bis(tert-butoxycarbonyl)-S-methylisothiourea (1.456 g, 5.02 mmol) in THF (25 mL) was added dropwise over 1 h. After 16 h, the reaction mixture was concentrated under reduced pressure and the residue was purified by flash chromatography (6% methanol, 4% triethylamine, 90% ethyl acetate), affording 12 as a pale yellow oil, 3.51 g (70%).

Example 2 General Procedure for the Preparation of 14

To a stirred solution of 12 (1.5 mmol) in THF (15 mL) at 60° C., a solution of the appropriate N,N′-bis(tert-butoxycarbonyl)-N-(alkyl)-S-methylisothiourea (1 mmol) in THF (5 mL) was added dropwise. The reaction mixtures were stirred at 60° C. for 16 h, cooled at rt and concentrated under reduced pressure. The crude mixtures were purified by flash chromatography, affording 14a-b as yellow oils.

NMR Data for Compounds 14a-b 2,6[(Di-tert-butoxycarbonyl)diimido]-3-benzyl-5-tert-butoxycarbonyl-1,3,5,7,16-pentaazacyclotetracosan-4-one (14a)

¹H NMR (CDCl₃) δ 12.06 (NH, br s), 8.73 (NH, br s), 8.06 (NH, br s), 7.26-7.24 (5H, m), 4.82 (2H, s), 3.47-3.32 (2H, m), 3.25-3.18 (2H, m), 3.00-2.93 (4H, m), 2.01-1.82 (4H, m), 1.48 (9H, s), 1.43 (9H, s), 1.41 (9H, s), 1.29-1.11 (20H, m). MS (ESI): m/z=772.1 [M+H]⁺.

2,6[Di-tert-butoxycarbonyl)diimido]-3-propargyl-5-tert-butoxycarbonyl-1,3,5,7,16-pentaazacyclotetracosan-4-one (14b)

¹H NMR (CDCl₃) δ 8.09 (NH, br s), 4.45 (2H, s), 3.50 (1H, s), 3.45-3.20 (4H, m), 3.25-3.15 (4H, m), 2.01-1.82 (4H, m), 1.48 (9H, s), 1.43 (9H, s), 1.41 (9H, s), 1.32-1.11 (20H, m). MS (ESI): m/z=720.2 [M+H]⁺.

Example 3 General Procedure for Synthesis of Compounds 4a-4-e

Compounds 3a-3e were treated with a 10% solution of freshly distilled TFA in dry DCM (30 mL for 1 mmol) and the reaction mixtures was stirred at rt under argon. After 24 h, the reaction mixtures were concentrated under reduced pressure giving the desired compounds as tri trifluoroacetate salts (brown oils), in quantitative yield. The mixtures were purified by semipreparative HPLC affording the final compounds as tri triformiate salts.

NMR Data for Compounds 15a-15e

2,6-Diimido-3-benzyl-1,3,5,7,16-pentaazacyclotetracosan-4-one tri trifluoroacetate (15a)

¹H NMR (CD₃)₂CO δ 8.25 (NH, br s), 7.75 (NH, br s), 7.44 (NH, br s), 7.35-7.32 (5H, m), 4.55-4.52 (2H, d, J=5 Hz), 3.75-3.44 (4H, m), 3.32-3.29 (4H, m), 1.64-1.57 (8H, m), 1.30 (16H, br s). MS (ESI): m/z=472.1 [M+H]⁺.

2,6-Diimido-3-propargyl-1,3,5,7,16-pentaazacyclotetracosan-4-one tri trifluoroacetate (15b)

¹H NMR (CD₃)₂CO δ 8.26 (NH, br s), 7.60 (NH, br s), 7.44 (NH, br s), 4.16-4.14 (2H, m), 3.48-3.45 (4H, m), 3.33-3.27 (4H, m), 2.89 (1H, s), 1.68-1.59 (8H, m), 1.35-1.29 (16H, m). MS (ESI): m/z=420.1 [M+H]⁺.

2,6-Diimido-3-(γ-methylallyl)-1,3,5,7,16-pentaazacyclotetracosan-4-one tri triformiate (15c)

¹H NMR (CD₃)₂CO δ 8.24 (NH, br s), 7.77 (NH, br s), 7.20 (NH, br s), 5.77-5.45 (2H, m), 3.74-3.71 (2H, m), 3.30-3.25 (4H, m), 3.19-3.12 (4H, m), 1.70-1.46 (12H, m), 1.34-1.26 (16H, m). MS (ESI): m/z=436.2 [M+H]⁺.

2,6-Diimido-3-(β-methylallyl)-1,3,5,7,16-pentaazacyclotetracosan-4-one tri triformiate (15d)

¹H NMR (CD₃)₂CO δ 8.30 (NH, br s), 7.58 (NH, br s), 4.93-4.88 (2H, d, J=10 Hz), 3.84-3.82 (2H, m), 3.46-3.40 (4H, m), 3.37-3.20 (4H, m), 1.72 (3H, s), 1.62 (8H, br s), 1.32-1.27 (16H, m). MS (ESI): m/z 436.3 [M+H]⁺.

2,6-Diimido-3-(γ,γ-dimethylallyl)-1,3,5,7,16-pentaazacyclotetracosan-4-one triformiate (15e)

¹H NMR (CD₃)₂CO δ 8.22 (NH, br s), 7.90 (NH, br s), 5.28-5.25 (1H, m), 3.74-3.71 (2H, m), 3.40-3.30 (4H, m), 3.20-3.10 (4H, m), 1.65-1.44 (14H, m), 1.30-1.28 (16H, m). MS (ESI): m/z=450.3 [M+H]⁺.

Biological Tests Determination of MICs by AFST-EUCAST Standard Methodology

Assay medium. The assay medium was RPMI 1604 without NaHCO₃ and with L-glutamine (Sigma Aldrich, Italy), buffered at pH 7.0 with 0.165 M morpholinepropanesulphonic acid (Sigma Aldrich, Italy) and supplemented with 2% (w/v) glucose. The medium, prepared as double-strength solution, was sterilized by filtration and diluted 1:2 (v/v) with the fungal inoculum prepared in sterile distilled water.

Preparation of Inoculate

The yeast isolates were grown on Sabouraud dextrose agar (Oxoid, Madrid, Spain) for 48 h at 37° C. before testing. Suspensions were prepared by combining five distinct colonies of each culture of >1 mm diameter. A spectrophotometric procedure for inoculum preparation was used. The final inoculum suspension, prepared in sterile distilled water, contained between 0.5·10⁵ and 2.5·10⁵ cfu/mL.

Antifungal Agents

Stock solutions of test compounds were prepared in 100% dimethyl sulfoxide. Stock solutions were prepared as 100× concentration relative to the highest concentration in the antifungal activity test, and frozen at −70° C. until used.

Susceptibility Testing

Sterile plastic micro titration plates containing flat-bottomed wells were used. The plates contained serial dilution of the antifungal agents with a volume of assay medium of 100 μL/well. Two drug-free medium wells were used as sterility and growth controls. The trays were inoculated with 100 μL/well of the final inoculum, with the exception of sterility control wells. The range of concentrations tested for each drug was 1.25-80 μM. The microtitration plates were incubated at 37° C. for 24 h. The minimal inhibitory concentrations (MICs) were determined at 24 h both visually and spectrophotometrically.

Visual Endpoint Determination

By visual endpoint determination, MICs were determined according to a S-1-R scale, with S (susceptible) indicating an optical clear culture, I (intermediate susceptibility) indicating a slightly hazy culture, and R (resistant) indicating no reduction in turbidity. The MIC₅₀ was defined as the lowest concentration of a drug which correspond to a S culture.

Spectrophotometric Endpoint Determination

Microtitration plates were stirred using a microtitration plate shaker before reading to ensure uniform turbidity. MICs were obtained by measuring the absorbance at 450 nm with a microtitration plate reader. The value of the blank was subtracted from reading of the rest of the wells. Two endpoints were defined for each antifungal agent tested, with MIC₈₀ indicating the lowest drug concentration resulting in a reduction of growth of 80% or more (determined spectrophotometrically) compared with the growth of the control, and MIC₅₀ indicating the lowest drug concentration resulting in a reduction in growth of 50% (determined spectrophotometrically) compared with the growth of the control. The MIC₅₀ was also defined as the spectrophotometric endpoint.

Results

The results of the biological tests are shown in Table 1 and Table 2. Compound 15e, bearing the most bulky side chain (a prenyl group), showed interesting activity toward C. albicans (20-40 μM), C. krusei and C. tropicalis, while C. parapsilosis and C. glabrata were low sensitive to such a compound (40-80 μM). Reducing the size of the unsaturated chain to a butenyl group (15c), activity underwent a significant increase showing very good values toward C. albicans (2.5 μM against all strains) and C. tropicalis (1.25 μM). C. krusei strains were also sensitive, but at a lower concentration (10 μM). Changing the butenyl chain into a methylpropenyl moiety (15d) caused a dramatic loss of activity against all fungal strains. The best activity for this compound was found toward C. albicans (MIC=20 μM toward the standard and 15T strains). A further reduction of the side chain size to a propargyl moiety as in 15b restored a good activity toward C. albicans (with the exception of C. albicans 4T that was resistant to such a compound) and C. tropicalis (5 μM). Finally, aromatisation of the side chain to a benzyl group (15a) led to activity data comparable to those found for the butenyl derivative 15c. In summary, both the butenyl and benzyl derivatives showed the best values for antifungal activity, followed by the propargyl compound that retained interesting activity toward a wide number of fungal strains.

TABLE 1 Antifungal activity of guazatine components and linear and cyclic guanidino derivatives. Antifungal activity, expressed as MIC₅₀ (μM)^(a) Candida species 15a 15b 15c 4d 15e F C. albicans ATCC 60193 2.5 2.5 2.5 20 40 0.8 C. albicans 4T 2.5 80 2.5 40 20 209 C. albicans 53T 2.5 5 2.5 40 20 418 C. albicans 15T 5 2.5 2.5 20 20 209 C. krusei ATCC 14243 20 80 10 40 10 209 C. krusei 193T 10 40 10 80 20 418 C. parapsilosis 80 40 >80 >80 >80 6.5 ATCC 34136 C. parapsilosis 64E 20 40 20 >80 >80 32 C. parapsilosis 81E 20 80 40 >80 40 13 C. glabrata 70E 40 80 40 80 80 209 C. tropicalis 86E 2.5 5 1.25 40 20 52 ^(a)MIC values were determined at 24 h both visually and spectrophotometrically. F is fluconazole.

TABLE 2 Antifungal activity of guazatine components and linear and cyclic guanidino derivatives.

Antifungal activity, expressed as MIC₅₀ (μM)^(a) Candida species 12c 12f 13a 13b 13d 13e 13f C. albicans ATCC 60193 20 80 2.5 2.5 2.5 20 40 C. albicans 4T 10 80 2.5 80 1.25 40 20 C. albicans 53T 10 80 2.5 5 2.5 40 20 C. albicans 15T 20 40 5 2.5 1.25 20 20 C. krusei ATCC 14243 5 40 20 80 5 40 10 C. krusei 193T 10 20 10 40 5 80 20 C. parapsilosis ATCC 34136 80 >80 80 40 5 >80 >80 C. parapsilosis 64E 5 >80 20 40 5 >80 >80 C. parapsilosis 81E 20 40 20 80 5 >80 40 C. glabrata 70E 20 80 40 80 20 80 80 C. tropicalis 86E 5 20 2.5 5 1.25 40 20 ^(a)MIC values were determined at 24 h both visually and spectrophotometrically.

BIBLIOGRAPHY

-   Chamilos, G.; Kontoyiannis, D. P. Curr. Opin. Infect. Dis. 2006, 19,     380. -   Aperis, G.; et al., Expert Opin. Investig. Drugs 2006, 15, 1319. -   Klepser, M. E. Pharmacotherapy 2006, 26, 68S. -   Pauli, A. Med. Res. Rev. 2006, 26, 223. -   Buxbaum, A.; et al., Antimicrob. Chemother. 2006, 58, 193. -   Jana, G. H.; Jain, S.; Arora, S. K.; Sinha, N. Bioorg. Med. Chem.     Lett. 2005, 15, 3592. -   Martin, D. W. et al., Proc. Natl. Acad. Sci. USA 1993, 90, 8377. -   Dreassi, E.; et al., J. Pharm. Biomed. Anal., in press. -   Sheehan, D. J.; Hitchcock, C. A.; Sibley, C. M. Clin. Microbiol.     Rev. 1999, 12, 40. -   Pfaller, M. A. et al., J. Clinical Microb. 1999, 37, 870. -   Herreros, E. et al., Antimicrob. Agents Chemother. 2001, 45, 3132. -   Deschenes, R. J.; et al., Antimicrob. Agents Chemother. 1999, 43,     1700. 

1. A compound having the general formula (9):

wherein R═H, propargyl, cyclopropylmethyl, γ-methylallyl, β-methylallyl or γ,γ-dimethylallyl, benzyl, but-2-enyl, isobutenyl, or prenyl; n₁ and n₂ are numbers equal or different comprised between 4 and 8, and any salts thereof.
 2. A compound having the general formula (10):

wherein R₁═H, propargyl, cyclopropylmethyl, γ-methylallyl, β-methylallyl or γ,γ-dimethylallyl; R₂═H, propargyl, cyclopropylmethyl, γ-methylallyl, β-methylallyl or γ,γ-dimethylallyl; n₁ and n₂ are numbers equal or different comprised between 1 and 3; and any salts thereof.
 3. A compound having the general formula (18):

wherein R₁═H, propargyl, cyclopropylmethyl, γ-methylallyl, β-methylallyl, γ,γ-dimethylallyl, methyl or ethyl; R₂═H, propargyl, cyclopropylmethyl, γ-methylallyl, β-methylallyl, γ,γ-dimethylallyl, methyl or ethyl; R₃═H, methyl, ethyl or benzyl; R₄-R₁₇ and R₁₉ are the same or each is independently H, methyl or ethyl; and any salts thereof.
 4. A compound having the general formula (19):

wherein R₁, R₂, R₁₈ and R₁₉═H; R₃═H, propargyl, cyclopropylmethyl, γ-methylallyl, β-methylallyl, γ,γ-dimethylallyl, methyl or ethyl; R₂₀═H, propargyl, cyclopropylmethyl, γ-methylallyl, β-methylallyl, γ,γ-dimethylallyl, methyl or ethyl; R₄-R₉ and R₁₀-R₁₇ are the same or each is independently H, methyl or ethyl; and any salts thereof.
 5. A compound having the general formula (20)

wherein R₁, R₂, R₁₆ and R₁₇═H; R₃ and R₁₈ are the same or each independently H, propargyl, cyclopropylmethyl, γ-methylallyl, β-methylallyl, γ,γ-dimethylallyl, methyl or ethyl; R₄-R₉ and R₁₀-R₁₅ are the same or each is independently H, methyl or ethyl; and any salts thereof.
 6. A compound having the general formula (21):

wherein R₁, R₂, R₁₇ and R₁₈═H; R₃═H, propargyl, cyclopropylmethyl, γ-methylallyl, β-methylallyl, γ,γ-dimethylallyl, methyl or ethyl; R₁₉═H, propargyl, cyclopropylmethyl, γ-methylallyl, β-methylallyl, γ,γ-dimethylallyl, methyl or ethyl; R₄-R₉ and R₁₀-R₁₆ are the same or each is independently H, methyl or ethyl; and any salts thereof.
 7. A compound having the general formula (22):

wherein R₁═H; R₂═H; R₁₈ and R₁₉═H; R₃═H, propargyl, cyclopropylmethyl, γ-methylallyl, β-methylallyl, γ,γ-dimethylallyl, methyl or ethyl; R₂₀═H, propargyl, cyclopropylmethyl, γ-methylallyl, β-methylallyl, γ,γ-dimethylallyl, methyl or ethyl; R₄-R₁₀ and R₁₁-R₁₇ are the same or each is independently H, methyl or ethyl; and any salts thereof.
 8. A compound having the general formula (23):

wherein R₁═H; R₂═H; R₂₀═H; R₃═H, propargyl, cyclopropylmethyl, γ-methylallyl, β-methylallyl, γ,γ-dimethylallyl, methyl or ethyl; R₁₉═H, propargyl, cyclopropylmethyl, γ-methylallyl, β-methylallyl, γ,γ-dimethylallyl, methyl or ethyl; R₄-R₁₀ and R₁₁-R₁₈ are the same or each is independently H, methyl or ethyl; and any salts thereof.
 9. A compound having the general formula (24):

wherein R₁═H; R₂═H; R₁₈═H; R₃═H, propargyl, cyclopropylmethyl, γ-methylallyl, β-methylallyl, γ,γ-dimethylallyl, methyl or ethyl; R₁₉═H, propargyl, cyclopropylmethyl, γ-methylallyl, β-methylallyl, γ,γ-dimethylallyl, methyl or ethyl; R₄-R₁₀ and R₁₁-R₁₇ are the same or each is independently H, methyl or ethyl; and any salts thereof.
 10. A compound having the general formula (25):

wherein R₁═H; R₂═H; R₂₁═H; R₃═H, propargyl, cyclopropylmethyl, γ-methylallyl, β-methylallyl, γ,γ-dimethylallyl, methyl or ethyl; R₂₂═H, propargyl, cyclopropylmethyl, γ-methylallyl, β-methylallyl, γ,γ-dimethylallyl, methyl or ethyl; R₄-R₁₁ and R₁₂-R₂₀ are the same or each is independently H, methyl or ethyl; and any salts thereof.
 11. A compound having the general formula (26):

wherein R₁═H; R₂═H; R₁₉ and R₂₀═H; R₃═H, propargyl, cyclopropylmethyl, γ-methylallyl, β-methylallyl, γ,γ-dimethylallyl, methyl or ethyl; R₂₁═H, propargyl, cyclopropylmethyl, γ-methylallyl, β-methylallyl, γ,γ-dimethylallyl, methyl or ethyl; R₄-R₁₁ and R₁₂-R₁₈ are the same or each is independently H, methyl or ethyl; and any salts thereof.
 12. A compound having the general formula (27):

wherein R₁═H; R₂═H; R₁₈ and R₁₉═H; R₃═H, propargyl, cyclopropylmethyl, γ-methylallyl, β-methylallyl, γ,γ-dimethylallyl, methyl or ethyl; R₂₀═H, propargyl, cyclopropylmethyl, γ-methylallyl, β-methylallyl, γ,γ-dimethylallyl, methyl or ethyl; R₄-R₁₁ and R₁₂-R₁₇ are the same or each is independently H, methyl or ethyl; and any salts thereof.
 13. A compound having the general formula (28):

wherein R₁═H, propargyl, cyclopropylmethyl, γ-methylallyl, β-methylallyl, γ,γ-dimethylallyl, methyl or ethyl; R₂═H, propargyl, cyclopropylmethyl, γ-methylallyl, β-methylallyl, γ,γ-dimethylallyl, methyl or ethyl; R₃═H, methyl, ethyl or benzyl; R₄-R₂₃ are the same or each is independently H, methyl or ethyl; and any salts thereof.
 14. A compound having the general formula (29):

wherein R₁═H, propargyl, cyclopropylmethyl, γ-methylallyl, β-methylallyl, γ,γ-dimethylallyl, methyl or ethyl; R₂═H, propargyl, cyclopropylmethyl, γ-methylallyl, β-methylallyl, γ,γ-dimethylallyl, methyl or ethyl; R₃═H, methyl, ethyl or benzyl; R₄-R₂₁ are the same or each is independently H, methyl or ethyl; and any salts thereof.
 15. A compound with the general formula (30):

wherein R₁═H, propargyl, cyclopropylmethyl, γ-methylallyl, β-methylallyl, γ,γ-dimethylallyl, methyl or ethyl; R₂═H, propargyl, cyclopropylmethyl, γ-methylallyl, β-methylallyl, γ,γ-dimethylallyl, methyl or ethyl; R₃═H, methyl, ethyl or benzyl; R₄-R₂₁ are the same or each is independently H, methyl or ethyl; and any salts thereof.
 16. A compound having the general formula (31):

R₁═H, propargyl, cyclopropylmethyl, γ-methylallyl, β-methylallyl, γ,γ-dimethylallyl, methyl or ethyl; R₂═H, propargyl, cyclopropylmethyl, γ-methylallyl, β-methylallyl, γ,γ-dimethylallyl, methyl or ethyl; R₃═H, methyl, ethyl or benzyl; R₄-R₂₂ are the same or each is independently H, methyl or ethyl; and any salts thereof.
 17. A compound having the general formula (32):

wherein R₁═H, propargyl, cyclopropylmethyl, γ-methylallyl, β-methylallyl, γ,γ-dimethylallyl, methyl or ethyl; R₂═H, propargyl, cyclopropylmethyl, γ-methylallyl, β-methylallyl, γ,γ-dimethylallyl, methyl or ethyl; R₃═H, methyl, ethyl or benzyl; R₄-R₂₀ are the same or each is independently H, methyl or ethyl; and any salts thereof.
 18. A compound having the general formula (33):

wherein R is methylcyclopropyl or prenyl. 19.-23. (canceled)
 24. A pharmaceutical composition comprising a compound according to claim
 1. 25. The pharmaceutical composition according to claim 24 further comprising at least one other compound with antifungal activity.
 26. A process for the preparation of a compound according to claim 1 comprising the following steps: a) reaction of a suitable amine R₁—NH₂ with a suitable S-methylisothiourea in a suitable solvent for obtaining compound 2

wherein n₁ and n₂ are 4 or 6, n₂ can be the same as or different from n₁; R₁═H, propargyl, cyclopropylmethyl, γ-methylallyl, β-methylallyl, γ,γ-dimethylallyl, methyl or ethyl; R₂═H, propargyl, cyclopropylmethyl, γ-methylallyl, β-methylallyl, γ,γ-dimethylallyl, methyl or ethyl; b) extract and/or purify compound 2 as obtained under a); c) allow compound 2 to react with an appropriate N,N′-bis(tert-butoxycarbonyl)-N-(alkyl)-S-methylisothiourea under conditions suitable for obtaining the compound 3, or 5-10 shown below:

wherein R₂═H, propargyl, cyclopropylmethyl, γ-methylallyl, β-methylallyl, γ,γ-dimethylallyl, methyl or ethyl; R₃═H, methyl, ethyl or benzyl; R₄-R₂₃═H, methyl or ethyl; R₄-R₂₃ can be same or different; d) purify compounds 3, 5-10 as under c); e) allow compounds 3, 5-10 to react under suitable conditions for obtaining the compound according to claim 1; f) extract and/or purify the compounds as obtained under e).
 27. An intermediate of formula 3, 5-10:

wherein R₂═H, propargyl, cyclopropylmethyl, γ-methylallyl, β-methylallyl, γ,γ-dimethylallyl, methyl or ethyl; R₃═H, methyl, ethyl or benzyl; R₄-R₂₃═H, methyl or ethyl; R₄-R₂₃ can be same or different. 